TM-5-3805-254-14-P-2
TRUCK, DUMP, 20 TON, 6X4, ON-OFF HIGHWAY 71,000 GVW, IHC MODEL F-5070 (CCE)
TECHNICAL MANUAL; OPERATOR’S, ORGANIZATIONAL, DIRECT SUPPORT, GENERAL SUPPORT AND DEPT MAINTENANCE MANUAL (INCLUDING REPAIR PARTS INFORMATION AND SUPPLEMENTAL MAINTENANCE INSTRUCTIONS)
JUNE 1980
TM-5-3805-254-14-P-2 - Page 850 of 894
TROUBLE SHOOTING
the units or be carried into the bearing by the lubricant
while in service. Dirt may enter through seals, breather or
even dirty containers used for addition or change of
lubricant.
Softer material such as dirt, dust, etc., usually forms
abrasive paste or lapping compounds within the bearings
themselves since the unit pressure between the balls and
raceways makes a perfect pulverizer. The rolling motion
tends to entrap and old the abrasives. As the balls and
raceways wear, the bearings become noisy. The lapping
action tends to increase rapidly as the fine steel from the
balls and rollway adds to the lapping material.
Hard, coarse material such as chips, etc., may enter
the bearings during assembly from hammers, drifts,
power chisels, etc., or be manufactured within the unit
during service from raking teeth, etc. These chips
produce small indentation in balls and races. Jamming of
these hard particles between balls and races may cause
the inner race to turn on shaft, or the outer race to turn in
the housing.
Fatigue:
All bearings are subject to fatigue and must be
replaced eventually. Your own operating experience will
dictate mileage replacement of bearings showing only
normal wear.
Corrosion:
Water, acid and corrosive materials formed by
deterioration of lubricant, will produce reddish-brown
coating and small etched holes over outer and exposed
surfaces of race. Corrosive oxides also act as lapping
agent.
Brinelling caused by improper assembly or removal
usually hammering with off-center blows.
Use drivers,
preferably under an arbor, or pullers.
Shaft Fits:
Excessive looseness under load is very objectionable
because it produces a creeping or slipping of the inner
ring on the rotating shaft. This causes the surface metal
of shafts to scrub or wear off.
Bearing fits on rotating shafts are usually specified as
tight. When play or looseness, even .001", exists
between the bearing and shaft, there is a very powerful
force tending to rotate the inner race on the shaft; this
force is caused by the looseness or lost motion between
the parts and disappears when no looseness exists.
Removal of Bearings:
It is far more difficult to remove bearings from a shaft
than to put them on. In most cases it is necessary to
remove the bearing by pulling on the outer-race which
can damage the balls or races.
Since such damage is
seldom visible, it does not become known until after
complete reassembly. It is good P.M. to replace most ball
bearings during the overhaul period. If a bearing is not
going to be replaced, avoid removal during low mileage
rebuild.
Interchangeability:
All ball bearings (whether manufactured here or
abroad) are interchangeable in regard to-standardized
dimensions, tolerances and fits. However, for a given
shaft size there are standard bearings for light, medium,
and heavy-duty service.
Numbers and symbols stamped on inner and outer
races of bearings designate size and type.
Numbering
systems
of
different
bearing
manufacturers, however, have not been standardized.
Consult interchangeable tables and use proper bearings
for replacement parts.
841
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